Speed control for packaging apparatus

ABSTRACT

An infeed conveyor for a packaging apparatus including a drive mechanism coupled to a power source for advancing articles into the packaging apparatus. The drive mechanism is operable to convert constant speed of the power source to a periodically varying speed of the conveyor to change the spacing of the articles from a first spacing on the conveyor to a second spacing in the packaging apparatus.

[451 Mar. 21, 1972 United States Patent Miller et al.

54] SPEED CONTROL FOR PACKAGING 3,269,086 8/1966 Cloots et a1..........................198/34 x FOREIGN PATENTS 0R APPLICATIONS APPARATUS [72] Invent: gf z i wg is??? Edgar 887,470 l/l962 Great Britain......................... g 895,528 5/1962 GreatBritain....................

[73] Assignee: Kraftco Corporation, Chicago, Ill.

[22] Filed: July 30, 1970 Primary Examiner-Theron E. Condon Assistant Examiner-Eugene F. Desmond Attorney-Luedeka, Fitch, Even and Tabin 211 Appl. No.:

[57] ABSTRACT An infeed conveyor for a packaging apparatus including a drive mechanism coupled to a power source for advancing ar- 198/209 ticles into the packagmg apparatus. The drive mechanism is operable to convert constant speed of the power source to a periodically varying speed of the conveyor to change the spac- [51] Int. [58] Field ofSearch References Cited mg of the articles from a first spacing on the conveyor to a second spacing in the packaging apparatus.

UNITED STATES PATENTS 2,602,276 Campbell.................................53/l82 7Claims,7Drawing Figures PAIENTEUMAR21 I972 v 3,650,089

sum 1 [IF 5 FIG] I NVE M11325 ATT Y5.

PATENTEDMAR21|972 3,650,089

SHEET 2 [1F 5 INVCNTOEE:

TT'YS.

SPEED CONTROL FOR PACKAGING APPARATUS The present invention relates generally to a packaging apparatus and, more particularly, to an improved infeed conveyor for transporting individual articles such as slices of cheese or the like into a wrapping station where they are wrapped in a flexible wrapping material. The latter is in the form of a continuous sheet and is advanced continuously into the wrapping station where it converges with a continuously advancing succession of the articles to be packaged and is wrapped around the articles.

In prior art apparatus for packaging cheese slices, the slices were supported in flat aligned relationship on a conveyor moving at uniform speed which was typically the same speed as that of the wrapping material so that the cheese and wrapping material entered the wrapping station and made contact or a marriage at the same speed. This resulted in a spacing of the cheese slices in the wrapping material which was the same as the spacing of the cheese slices on the conveyor. After the slices made contact with the wrapping material, the latter was formed in a continuous tube around the spaced cheese slices and then they progressed from the wrapping station to a sealing and cutting station where the tube was sealed and then severed between adjacent slices to form separate packages. In the prior art apparatus, the space between the cheese slices both on the conveyor and within the continuously formed tube of wrapping material was small so that, when the tube was sealed and severed between slices, a neat package was formed wherein the cheese slice occupied essentially the entire space between the seals at each end of the package.

Cheese slices are now available in different sizes and shapes, particularly in different lengths and, in the interest of economy. it is desirable that the same apparatus be utilized for wrapping all such slices while maintaining'an essentially filled package having a neat seal. Accordingly, it is an object of the invention to provide a novel conveyor apparatus capable of being utilized for wrapping cheese slices of different'lengths while insuring that the spacing between adjacent slices within the flexible wrapping material tube remains essentially the same.

It is a further object of the present invention to provide an apparatus for packaging articles of various lengths in neat uniform packages.

Another object of the present invention'is to provide an apparatus which is readily adaptable to the packaging of articles of different lengths as measured in the direction of movement of the articles.

These and other objects of the present invention will become apparent in connection with the following detailed description and the drawings in which:

FIG. 1 is a perspective view of a wrapping station of a machine embodying the novel features of the present invention;

FIG. 2 is a perspective view, partially exploded, of a portion of the apparatus of the present invention;

FIG. 3 is an elevational view partly in cross section of a portion of the apparatus of FIG. 1 taken along line 3-3 of FIG. 1;

FIG. 4 is an elevational view of a portion ofthe'apparatus taken along line 4-4 of FIG. 3;

FIG. 5 is a partial elevational view of a portion of the apparatus taken along line 5-5 of FIG. 4;

FIG. 6 is a partial sectional view of a portion of the apparatus taken along line 6-6 of FIG. 2; and

FIG. 7 is a fragmentary view, partially in cross section of a portion of the apparatus taken along line 7-7 of FIG. 6.

The invention is shown in the drawings for purposesof illustration for use with an apparatus l0 for packaging articles. Although the apparatus of the present invention is illustrated as wrapping slices of cheese 24, it could be employed for wrapping other articles such as slices of meat or for thicker articles not in slice form. The apparatus 10 includes a housing 12 which supports a roll of transparent wrapping material 14 and a series of rolls 18 for feeding the wrapping material at a constant speed to a wrapping station 16 in a manner well known in the art. At the wrapping station the wrapping material is formed to provide an elongated continuous tube enclosing the slices, with theslices spaced apart and aligned within the tube. The operation of the wrapping station is set forth in more detail in copending application Ser. No. 65,814, filed on Aug. 21, 1970, assigned to the assignee of the present invention and entitled Former for New Single Slice Package."

The slices are advanced to the wrapping station 16 by a conveyor 20 having spaced lugs 22, each of which engages the trailing edge of a slice of cheese 24 to locate the slice on the conveyor as it advances. After each cheese slice contacts the wrapping material and as the tube is formed around the slice, the slice leaves the conveyor and control of the advance of the slice passes from the conveyor to the wrapping material, in effect forming a marriage between the material and the slice. The conveyor 20 moves continuously in a forward direction to advance successive slices of cheese 24 toward the wrapping station 16.

The wrapping apparatus 10 and conveyor 20 are adapted to handle cheese slices of difierent lengths such as, for example, slices 4 inch in length and 8 inch in length, although it is to be understood that, for any given production schedule, slices of only one length are wrapped and not an interrnixture of the two. The lugs 22 of the conveyor 20 are spaced somewhat over 8 inches apart, in the example given, to accommodate the longer slices; when the shorter or 4 inch slices are wrapped, each cheese slice thus occupies less than one-half the distance between adjacent lugs 22.

In order to form neat packages, it is desirable that each slice engage the flexible wrapping material, while moving at substantially the same speed as the speed of the wrapping material 14, which is constant, thereby avoiding bending and tearing of the slices and efiecting a smooth transfer of the control of the movement of the slice from the conveyor to the wrapping material. However, it is also desirable that the space between slices as ultimately arranged on the wrapping material be only slightly'greater than that needed to make a seal between slices. Thus, where there is a substantial distance between slices on the conveyor, such as in the illustrated example best seen in FIG. 3, it is desirable that this space be substantially reduced in the placing of the slices on the wrapping material to avoid excess wrapping material in each package. It will be appreciated that if both the conveyor 20 and wrapping material 14 move at the same constant speed, when slices 4 inches in length are packaged, there will be 4 inches or more of wrapping material in each package in excess of the length of the slice. This situation could be remedied by dismantling the conveyor and substituting a different carrier with more closely spaced lugs and replacing one or more gears, but this would necessitate a long and costly shutdown of the line each time such a change was made.

Accordingly, the present invention contemplates the provision of a novel drive means 26 (FIG. 2) for driving the conveyor 20 at an average speed greater than the speed of the flexible wrapping material 14 when the shorter slices are being packaged and for varying the speed of the conveyor from the speed of the flexible wrapping material to higher speeds and then back to the same speed as that of the wrapping material 14 as eachslice contacts and forms the marriage with the wrapping material. Thus, while the conveyor functions to .close the gap between slices as they are arranged on the conveyor, this is donewith little or no slippage between the wrapping material and the respective slices at the time the slices are transferred to the wrapping material.

The novel drive means 26 is readily adjustable so that the:

ing between the slices in the tube of wrapping material, thus assuring neat packages after sealing and severing.

Referring to FIG. 1, it will be seen that the roll of flexible wrapping material 14 and the various rolls 18 for feeding it into the wrapping station 16, are mounted on a narrow vertical wall 13 of the housing 12 for rotation about parallel horizontal axes. A former 17 for the wrapping material is also mounted on the vertical wall 13 at the wrapping station by means of a pair of cantilever rods 28. The details of the wrapping station 16 and the operation of the apparatus for drawing the flexible material over the rolls and the former do not form part of the present invention and are described in copending US. Pat. application Ser. No. 860,508, filed Sept. 24, 1969, now US. Pat. No. 3,544,340, issued Dec. 1, 1970, entitled Cheese Packaging Method and Apparatus. It is noted, however, that the wrapping material is advanced through the wrapping station 16 at a constant linear rate of speed, although the constant speed may vary depending upon the length of slices to be wrapped.

The conveyor 20 (FIG. 3) is of the endless type having a horizontal top surface with the lugs 22 spaced equally along its entire length for positioning cheese slices. Each lug has a flat leading face 23 for engaging the trailing edge of a cheese slice lying on the top surface of the conveyor. The latter also includes a roller chain 30 which extends around and is stretched between a drive sprocket 32 and an additional idler sprocket (not shown). The drive sprocket constitutes an output member of the drive means 26.

Referring now to FIG. 2, the improved drive means 26 with its output sprocket 32 is shown in perspective with some parts exploded to show more clearly how they relate to each other. In the illustrated embodiment, the drive means is in the form of a gear train which converts the motion of a constant speed power source to periodic motion at the conveyor 20. The power source for the conveyor herein is an electric motor 34 which operates at a constant speed and has a sprocket 38 fast on its drive shaft 36. In the gear train which is described below, the axes of all shafts are parallel to each other and to the axes of the motor and the drive sprocket 32 for the conveyor chain 30.

The motor sprocket 38 is connected by a chain 44 to a sprocket 40 which is fixed by a spline on a shaft 42 rotatably supported at one end in a gear reducer 43 and at the other end in a suitable bearing 45 mounted inside the housing (FIG. 4) above the motor 34. The gear reducer 43 relates to other parts of the packaging apparatus and does not form part of the present invention. As viewed in FIG. 2, the rotation of the motor 34 and consequently the shaft 42 is in a clockwise direction.

Also fast on the shaft 42 for rotation therewith at a constant speed is a spur gear 46 which forms an input or one terminal gear of a differential system and meshes with a second spur gear 48 shown exploded from its operative position for clarity and acting as a planet carrier, the latter also being rotated at a constant speed although in a counterclockwise direction. The carrier gear 48 is joumaled at its center on a shaft 50 by means of a bearing 52 which prevents axial movement of the gear along the shaft. Eccentrically of its center, the carrier gear 48 is formed with an opening 54 which rotatably receives a shaft 56 of a planet gear 60. The latter is fast on one end of its shaft on one side of the carrier gear. The other end of the shaft on the other side of the carrier gear carries a cam follower arm 58 which is rigidly secured to it by a clamp 59 so that movement of the cam follower arm causes rotational movement of the shaft relative to the carrier gear. Suitable spacers 61 are provided on the planet shaft 56 between the respective elements to assure free rotation of the shaft 56 in the opening 54 (FIG. 2).

The planet gear 60 meshes with another spur gear 62 fast on the same shaft 50 which supports the carrier gear 48. The gear 62 may be considered as the sun gear and also the output terminal gear of the differential and rotates with the shaft 50 independently of the carrier gear 48, the shaft 50 being journaled in suitable spaced bearings 64 (FIG. 4).

Secured on the shaft 50 (FIG. 2) for rotation with the sun gear 62 is a helical gear 66 which meshes with a second helical gear joumaled on a fixed shaft 70 above the first helical gear 66 by a suitable bearing 72. The second helical gear 68 in turn meshes with a third helical gear 74 which is fast on a second fixed shaft 78 rotatably supported above the gear 68. The third helical gear 74 differs from the previously described helical gears in the train due to its greater axial length. The purpose of this greater length is to permit adjustment, as will be more fully explained hereinafter in connection with the operation of the conveyor.

The third helical gear 74 meshes with a fourth helical gear 82 which is coupled by a spline on a shaft 84 for rotation therewith and for adjustment axially therealong. The shaft 84 is journaled in suitable bearings 86 (FIG. 6) and extends through the housing wall to a point adjacent the wrapping station 16 where the output sprocket 32 is secured to it for rotation with the fourth helical gear 82.

Although only one conveyor and wrapping apparatus are shown in FIG. 1, it is contemplated that a second conveyor and wrapping apparatus be provided on the other side of the upstanding center housing wall 13. The same motor and same differential gearing are utilized to drive that conveyor, the gear train beyond the second helical gear 68 being duplicated for this purpose as shown in FIGS. 2, 4, and 6 where the duplicated parts for the second conveyor bear similar reference numbers with a suffix a. 7

As can best be seen in FIGS. 3 and 4, the cam follower arm 58 carries a roller 88 at the end of the arm remote from the shaft 56 and the roller is received in a groove of a cam plate 90. The groove has parallel walls defining a noncircular track 92 for the roller. Suitable slots 94 are formed in the plate for mounting it on the inner side of the side wall of the housing 12, as by bolts 96, the track 92 being on the inner surface of the cam plate facing the cam follower arm 58 and the gear train. The cam plate also provides a bearing for one end of the planet carrier shaft 50 which is joumaled in the center of the plate.

Referring now to FIGS. 2, 3, and 5, it can be seen that, during rotation of the carrier gear 48, the cam follower arm 58 and the planet gear 60 on the shaft 56 revolve with it about the carrier shaft 50 which carries the sun gear 62 and the first helical gear 66. So long as the planet gear does not rotate about its shaft relative to the carrier gear, the sun gear and first helical gear will rotate at the same speed as the carrier gear. However, as the planet gear is rotated in one direction or other due to variations in the cam track 92, the speed of the sun gear and first helical gear is increased or decreased respectively relative to the speed of the carrier gear. The shape of the track 92 thus determines the relative movement of the planet and sun gears 60 and 62 and the relative speeds of rotation of the carrier gear 48 and the first helical gear.

Assuming for the moment that the track 92 is circular and remains with its geometric center on the axis of rotation of the carrier gear 48, there will be no relative rotation between the planet and sun gears 60 and 62 since the cam follower ann 58 will maintain the same angle relative to a line between the axes of the two gears during each revolution of the carrier gear 48. In other words, with a circular cam path, the carrier gear will cause the planet gear shaft 56 to rotate through one complete revolution carrying the planet gear 60, which thereby is prevented from moving relative to the carrier gear. The planet gear 60 is at the same time meshed with the sun gear 62 in a locked position. Therefore, the rotation of the planet gear 60 with the carrier gear 48 through one complete rotation will cause the sun gear 62 to be rotated in the same direction through one complete rotation at the same angular velocity as the gear 48. In the meantime the planet gear orbits about the sun gear with no relative rotation between the two. If there were no restriction, as by the cam follower arm 58 on rotation of the planet gear 60, it would rotate both with and relative to the carrier gear 48 and would orbit around the sun gear 62 meshing with but causing no rotation of that gear. A circular cam path might therefore be desirable when wrapping slices of cheese 8 inches in length in the example given.

When, as in the present case, the cam track 92 is of muchcular shape, all other conditions being the same, there will be in the course of one revolution of the gear carrier 48, points where there will be no relative rotation between the planet and sun gears 60 and 62, as when the radius of the track 92 is a constant value, and there will be relative rotation between those gears at the portions of the track 92 where the radius is either decreasing or increasing. The result of such movement is that the sun gear 62 still rotates through only one complete rotation while the planet gear 60 revolves through one revolution during each revolution of the carrier gear 48. However, during that revolution of the carrier gear, the angular velocity of the sun gear about its axis will not be a constant equal to the constant angular velocity of the axis of the carrier gear 48, but will vary depending on whether the radius of the track 92 is increasing or decreasing.

In the illustrated embodiment, the cam track 92 is oval in shape. It is symmetrical about its major axis and its minor axis which intersect the axis of rotation of the carrier gear 48 and the sun and first helical gears 62 and 66. Referring to FIG. 3, when the carrier gear 48 rotates in a counterclockwise direction at a constant angular velocity, the relative speed of rotation of the sun gear 62 will be less than the speed of rotation of the carrier gear when the follower roller 88 engages a portion of the track 92 with an increasing radius; it will be equal to the angular speed of rotation of the carrier gear when the roller engages portions of the track 92 with a constant radius; and it will be greater than the angular speed of rotation of the carrier gear in the areas where the roller engages a portion of the track with a decreasing radius.

The sun gear 62 being connected directly to the output sprocket 32 through the gear train, the sprocket has the same cyclic or periodic motion as the sun gear but at different speed determined by the ratios of the various gears. Although many cam track configurations may be employed in the present invention, the oval track shown in FIG. 3 is illustrated as an example of a simple symmetrical shape which is suitable for the movement desired when the lugs 22 of the conveyor are spaced approximately 8 inches apart but the slice to be wrapped is only 4 inches in length. The portion of the track 92 where the radius of the track is increasing is the portion where the speed of the conveyor is the slowest and where it is equal to the speed of the wrapping material 14. This effect is achieved by employing a rate of change of the radius of the track with respect to time which causes the rotation of the cam follower arm 58 relative to the carrier gear 48 to be a constant. At all other points on the track 92, including the areas of constant radius, the speed of the conveyor exceeds the speed of the wrapping material.

In the embodiment illustrated where the track is of an oval form having two areas of increasing radius and two areas of decreasing radius, one complete rotation of the carrier and planet gears 48 and 60 causes the conveyor to move through two cycles of periodic motion. Thus, in the course of one orbit of the planet gear 60, two slices 24 of. cheese will be moved from the conveyor as shown in FIG. 3 into the wrapping station 16. The periodic motion caused by the cam follower arm 58 will have the effect both of advancing the conveyor at an average speed higher than the constant speed of the flexible wrapping material 14 in order to compensate for the substantial space between the cheese slices on the conveyor, and of advancing each cheese slice at substantially the same speed as the speed of the flexible wrapping material during the short period of time in which the slice contacts and becomes married to the wrapping material.

From the above explanation of the operation of the apparatus, it will be apparent that the periodic motion imparted to the conveyor 20 may be altered by substituting tracks 92 of different shape. Such substitution is easily accomplished by the removal of the bolts 96 and replacement of the cam plate by a different plate. Thus, the variations in speed of the conveyor can be controlled so that different lengths of cheese slices can be inserted into the wrapping station while maintaining the interval of the slices within the wrapping material at the desired value for achieving neat packages without waste of wrapping material. As previously mentioned, if the cheese slices were to occupy substantially the entire space between adjacent lugs of the conveyor, a circular cam track may be used to impart constant angular rotation to the entire gear train and eliminate the periodic motion of the conveyor, resulting in a movement of the conveyor at a constant velocity. The constant velocity imparted by a circular cam track would be equal to the average velocity of the conveyor imparted by the oval track 92. In order to effect a marriage without slippage in such circumstances, the speed of the wrapping material should be increased to the same constant speed as the conveyor.

It will further be evident from the operation of the apparatus disclosed herein that the coordination between the position of the lugs 22 and the point of the periodic cycle at which the conveyor is being advanced at substantially the same speed as that of the wrapping material 14 is a critical factor if the buckling of the cheese slices or slippage of the slices relative to the wrapping material is to be avoided. In order that the initial contact of the cheese slice 24 with the wrapping material coincides exactly with the time at which the conveyor is moving at the proper speed for a marriage without slippage between the cheese slice and the wrapping material, an adjusting mechanism, illustrated in FIG. 6, is provided for changing the position of the conveyor relative to the position of the cam follower arm 58 while the cam follower remains immobile. This mechanism is shown in duplicate for the two conveyors mentioned earlier, and each may be adjusted independently of the other. The operation of only one side of the adjusting mechanism will be described, it being understood that the operation of the other side is essentially identical.

As stated earlier and illustrated in FIG. 6, one helical gear 74 has a substantial axial length. It meshes directly with the helical gear 82 which is mounted on the shaft 84 for output sprocket 32. The gear 82 is spline coupled to the shaft as indicated at !00 (FIG. 7). Further, a plate 104 secured to the gear has a flange 102 spaced from the gear and cooperating with it to define an outwardly opening groove to receive the periphery of an adjusting disk 120.

The axial position of the adjusting disk 120 is varied by turning an adjustment screw which is threaded into a collar 112 rigidly affixed and extending through the wall of the housing 12. The adjustment screw and collar are finely threaded to facilitate minute adjustment of the position of the disk and, thus, the position of the helical gear 82. The disk is rotatably mounted on an unthreaded extension of the adjusting screw 114 which rotatably receives a hub 118 secured to the disk, the hub and disk being held against movement axially of the adjustment screw. In order to assure that the adjustment screw maintains the disk in, the desired axial position, a locking means in the form of a cylindrical collar 122 is positioned on the screw and abuts the fixed threaded collar 112 described earlier. A locking collar 124 is threaded onto the adjustment screw and positioned so that it can be tightened down onto the cylindrical collar 122, causing the threads of the screw to bind against the locking collar 124. The locking collar is further provided with a handle 126 to facilitate locking and unlocking of the adjustment screw in order to adjust the position of the gear 82.

When it is desired to change the position of the conveyor relative to the cam follower and the apparatus is standing still, the handle of the locking collar 124 is moved to loosen the pressure on the threads of the adjustment screw. The adjustment screw 1 10 is then threaded in the desired direction relative to the fixed collar by means of the knob 128 provided on the outside of the housing.

Movement of the adjustment screw in the axial direction causes the disk to move the helical gear 82 either up or down as seen in FIG. 6. Consequently, the gear is moved not only along the shaft 84 but also axially with respect to the elongated face 80 of the helical gear 74. In doing so, the point of meshing of the gear 82 and the gear 74 is altered so that there is a rotation of the shaft 84 and consequently a movement of output sprocket 32 driving the conveyor. If the gears mesh in the manner shown in FIG. 6 and the gear 74 is held fixed due to its linkage with the remainder of the gear train and the motor, a movement of the gear 82 upwardly will cause a rotational movement of the sprocket 32 as seen in FIG. 2 in a counterclockwise direction thereby moving the conveyor backward with respect to the position of the cam follower arm 58 which remains in a fixed position. Conversely, a movement downwardly in FIG. 6 will cause the gear 82 and consequently the shaft 84 and sprocket 32 to rotate clockwise as seen in FIG. 2 resulting in a forward motion of the conveyor relative to the cam follower arm 58.

The apparatus disclosed herein is an adaptable and versatile packaging apparatus capable of handling different sizes of objects to be packaged with a minimum of inconvenience in converting from one size to another. The conversion of the movement of the infeed conveyor to the desired pattern is accomplished merely by changing a cam plate conveniently located near the outside of the apparatus. The only other adjustment necessary is to select the desired constant speed for the flexible wrapping material to be fed into the wrapping station. The features incorporated in the apparatus provide low cost conversion from one size of package to another and a minimum of down time for such conversion.

While a preferred embodiment has been shown and described, it will be understood that there is no intent to limit the invention by such disclosure but, rather, it is intended to cover all modifications and alternate constructions falling within the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. In an apparatus for packaging articles, the combination of a wrapping station, means for supporting and feeding a continuous sheet of flexible wrapping material into and through said wrapping station at a predetermined constant linear velocity,

an endless conveyor having a portion extending into said wrapping station and supporting a plurality of said articles in aligned uniformly spaced relationship for movement in the same direction as the wrapping material and successively into contact with the wrapping material, and

a drive mechanism coupled to said conveyor and imparting to the conveyor a cyclic motion for advancing the conveyor continuously first at said predetermined velocity during a period of contact of each article with both the conveyor and the wrapping material, next at a higher velocity to reduce the spacing between that article and the next successive article, and then at a velocity decreasing to said predetermined velocity.

2. The apparatus defined in claim 1, wherein said drive mechanism includes differential gearing having first and second terminal members rotatable about parallel axes,

a carrier mounted to rotate about the axis of said second terminal member and having a driving connection with said first terminal member,

a shaft joumaled in said carrier and rotatable about an axis parallel to said first terminal axis,

an intermediate driving member on said shaft and having a driving connection with said second terminal member, and

means controlling the angular position of said shaft and said intermediate member relative to said carrier and operable to vary such angular position during rotation of the carrier to provide a corresponding variation in the angular velocity of said second terminal member relative to the angular velocity of said first terminal member.

3. The apparatus defined in claim 2, wherein said shaft of said intermediate member carries a follower, and a cam is mounted adjacent the path of said follower during rotation of said carrier and engages said follower to vary the angular position of the shaft and the follower relative to the carrier.

4. The apparatus defined in claim 3, wherein said cam provides an endless stationary cam track symmetrical about a center on the axis of said carrier and imparting to said cam follower during each revolution of the carrier similar periodic variations of angular position relative to the carrier.

5. The apparatus defined in claim 4, wherein said cam track is oval in shape to provide two cycles of periodic motion during each revolution of said carrier.

6. The apparatus defined in claim 2, wherein said drive mechanism includes a rotary output member coupled to said conveyor and drive elements coupling said second terminal member of said differential to said output member and including means for adjusting the relative angular positions of said second terminal member and said output member to advance and retract the position of said conveyor with respect to said wrapping material.

7. Packaging apparatus having, in combination, an endless conveyor for advancing articles to be packaged into an operating station,

article engaging means at said station movable at a constant velocity and adapted to receive successive articles at said station spaced apart by first predetermined equal intervals, said conveyor having article engaging members spaced apart equal distances along the conveyor and adapted to receive said articles with the articles spaced apart by second predetermined equal intervals different from said first intervals,

a source of constant speed rotary power, and

a drive mechanism coupling said power source and said conveyorand operable to convert the constant speed of the power source to a periodically varying speed of said conveyor to change the spacing of said articles from said second intervals to said first intervals and bring the articles to said constant velocity as the articles reach said station and contact said article engaging means. 

1. In an apparatus for packaging articles, the combination of a wrapping station, means for supporting and feeding a continuous sheet of flexible wrapping material into and through said wrapping station at a predetermined constant linear velocity, an endless conveyor having a portion extending into said wrapping station and supporting a plurality of said articles in aligned uniformly spaced relationship for movement in the same direction as the wrapping material and successively into contact with the wrapping material, and a drive mechanism coupled to said conveyor and imparting to the conveyor a cyclic motion for advancing the conveyor continuously first at said predetermined velocity during a period of contact of each article with both the conveyor and the wrapping material, next at a higher velocity to reduce the spacing between that article and the next successive article, and then at a velocity decreasing to said predetermined velocity.
 2. The apparatus defined in claim 1, wherein said drive mechanism includes differential gearing having first and second terminal members rotatable about parallel axes, a carrier mounted to rotate about the axis of said second terminal member and having a driving connection with said first terminal member, a shaft journaled in said carrier and rotatable about an axis parallel to said first terminal axis, an intermediate driving member on said shaft and having a driving connection with said second terminal member, and means controlling the angular position of said shaft and said intermediate member relative to said carrier and operable to vary such angular position during rotation of the carrier to provide a corresponding variation in the angular velocity of said second terminal member relative to the angular velocity of said first terminal member.
 3. The apparatus defined in claim 2, wherein said shaft of said intermediate member carries a follower, and a cam is mounted adjacent the path of said follower during rotation of said carrier and engages said follower to vary the angular position of the shaft and the follower relative to the carrier.
 4. The apparatus defined in claim 3, wherein said cam provides an endless stationary cam track symmetrical about a center on the axis of said carrier and imparting to said cam follower during each revolution of the carrier similar periodic variations of angular position relative to the carrier.
 5. The apparatus defined in claim 4, wherein said cam track is oval in shape to provide two cycles of periodic motion during each revolution of said carrier.
 6. The apparatus defined in claim 2, wherein said drive mechanism includes a rotary output member coupled to said conveyor and drive elements coupling said second terminal member of said differential to said output member and including means for adjusting the relative angular positions of said second terminal member and said output member to advance and retract the position of said conveyor with respect to said wrapping material.
 7. Packaging apparatus having, in combination, an endless conveyor for advancing articles to be packaGed into an operating station, article engaging means at said station movable at a constant velocity and adapted to receive successive articles at said station spaced apart by first predetermined equal intervals, said conveyor having article engaging members spaced apart equal distances along the conveyor and adapted to receive said articles with the articles spaced apart by second predetermined equal intervals different from said first intervals, a source of constant speed rotary power, and a drive mechanism coupling said power source and said conveyor and operable to convert the constant speed of the power source to a periodically varying speed of said conveyor to change the spacing of said articles from said second intervals to said first intervals and bring the articles to said constant velocity as the articles reach said station and contact said article engaging means. 